Thickness gauge



FIG. 1 is a perspective view from above the front and a first side;

FIG. 2 is a plan view;

FIG. 3 is a view from beneath;

FIG. 4 is a view from the first side, the opposite side being a mirrorimage;

FIG. 5 is a view from the back; and,

FIG. 6 is a view from the front.

The ornamental design for a thickness gauge, as shown and described. 